2-(omega-substituted vinylene)-3, 3-disubstituted-3h-indoles



United States Patent Ofiice 3,346,571 Patented Oct. 10, 1967 3,346,571 Z-(OMEGA-SUBSTITUTED VINYLENE)-3,3- DISUBSTITUTED-SH-INDOLES Sydney M. Spatz, Buffalo, and Russell 1. Steiner, Williamsville, N.Y., assignors to Allied Chemical Corporation,

New York, N.Y., a corporation of New York No Drawing. Filed June 5, 1963, Ser. No. 285,563 8 Claims. (Cl. 260-240) This invention relates to novel derivatives of 3H-indole. It relates more particularly to novel 3,3-di-substituted 3H- indole compounds having a vinylene-containing substituent attached by a vinylene group to the 2-position of the indole nucleus, and to processes for the preparation thereof.

An object of the present invention is to provide novel compounds which are derivatives of 3,3-disubstituted 3H- indole and especially of 3,3-dimethyl-3H-indole.

A further object of the present invention is to provide novel electron donor compounds which are lightly colored or substantially colorless but which when contacted with acidic electron acceptors produce intense colorations in the yellow to red portion of the visible spectrum.

Another object of the present invention is to provide novel compounds of said type which when used as color precursors in manifold record systems, for example of the type disclosed in U.S. Patents 2,505,470 and 2,548,- 366, give rise to intense red to yellow colorations.

Still another object of the present invention is to provide novel electron donor compounds of said type which are derivatives of 3,3-disubstituted 3H-indole where a vinylene containing substituent which imparts color forming resonance to the compound when contacted with acid electron acceptors is linked to the 2-position of the indole nucleus by a vinylene group.

An additional object of this invention is to provide processes for the preparation of said novel compounds.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

It is known to produce electron donor compounds which are lightly colored to substantially colorless but which produce coloredcompositions when contacted with acidic electron acceptors such as kaolin, bentonite and other acidic clays, zinc sulfide, calcium fluoride, and organic acids (e.g. tannic acid, benzoic acid and succinic acid).

The valuable characteristics of said known chromogenic compounds have led to the development of compositions useful in the preparation of the so-called colorless carbon papers and variations thereof. For example, impact printing papers and duplicating manifold record systems of this type are disclosed in US. Patent 2,505,470, wherein a solution of N-bis(p-dimethylaminophenyl)- methyl aniline (as chromogenic electron donor compound) is provided in the form of discrete particles in conjunction with a solid insulating material including an organic hydrophilic film-forming material and an acidic clay. Upon pressure by a stylus or impact, as by a typewriter key, combination of the chromogenic compound with the acidic electron accepting clay takes place, producing a blue colored mark. And in US. Patent 2,548,- 366 systems of this type are disclosed wherein the rear surface of each top sheet of a series of overlying sheets is coated with a dispersion of a suitable solution of the chromogenic substance in a rupturable hydrophilic colloid film, and the adjacent surface of the next underlying sheet is coated or filled with an acidic electron-accepting clay; so that pressure of a stylus or impact upon the top sheet causes color formation on the surface containing the acidic clay at the points of pressure or impact.

Other uses for such electron donor compounds in combination with acidic electron acceptor material have been developed. But, so far as we are aware, all of the compounds of this type heretofore known (such as crystal violet lactone and the compounds of US Patents 2,474,- 084; 2,505,470; 2,828,341; 2,828,342; 2,900,388; 2,948- 753; 2,981,733; 2,981,738 and 2,983,756) produce colorations limited mainly to the blue to green range of the visible spectrum; no compounds which give yellow or red or black colorations have heretofore been produced, despite the desirability of extending the range of colors to include them.

We have made the surprising discovery that a novel class of compounds, namely, 2-omega-substituted vinylene derivatives of 3,3-disubstituted 3H-indole, and especially of 3,3-dialkyl-3H-indole, in which a cyclic radical containing a nitrogen, oxygen, sulfur or selenium atom is connected to the Z-carbon atom of the indole nucleus through a vinylene radical (an ethylene group or a chain of two to five ethylene groups) in such manner that said nitrogen, oxygen, sulfur o-r selenium atom is linked to the indole nitrogen atom by a conjugated chain of an odd number of carbon atoms (including carbon atoms of the cyclic radical), possesses advantageous properties, which render them of particular value for the above uses, and especially for the production of yellow to red colorations. (As employed herein, including the claims, the term vinylene radical denotes the group (CH=CH) wherein I7. is 1 to 5.)

As indicated above, the compounds of the present invention are characterized by having a conjugated oddnumbered methine chain linking the indolyl nitrogen with the nitrogen, oxygen, sulfur or selenium atom at the other end of the chain. In contrast to the cyanine dyes, which require a tertiary and a quaternary nitrogen (or an oxygen and a quaternary nitrogen) to be linked by an odd numbered methine chain, the color precursors of this invention have at the ends of the methine chain two ternary nitrogen atoms, or one ternary and one secondary nitrogen atom, or one ternary nitrogen atom and an oxygen, sulfur or selenium atom.

The preferred compounds of our invention are slightly colored or substantially colorless. When protonated, i.e., when contacted with an acidic electron accepting substance, they produce generally deep shades of yellow or red which are generally stable and fast to light.

The compounds of the present invention are soluble in a wide variety of solvents. Thus they have substantial solubility in not only the usual solvents (such as benzene, toluene, dioctyl-phthalate, chlorinated biphenyls and the like) but also they possess outstanding solubility in petroleum hydrocarbon solvents such as kerosene, white mineral oil and naphthas as well as alcoholic solvents such as methanol, ethanol, diethylene glycol, glycerine and the like. These and analogous advantageous properties render the novel class of compounds of this invention eminently useful in extending the range of colorations obtainable in systems and compositions of the above described types. Hence these novel compounds are useful in the formation of stable deep yellow to red colored compounds by contact with electron acceptor or acidic materials which cause the protonation of the indolyl nitrogen and give rise to resonating structures with the development or the intensification of the deep color of the resultant protonated compounds.

Thus, the novel compound characterized by structure:

u converted to the following resonating structure, which is deeply colored:

Similarly, the colorless compound characterized by the structure:

T ?-C2H5 COH=CH-CH=CH- N on being protonated, is converted to highly colored re sonatin-g structure:

(Lon-r5 And the compound characterized by the structure:

GHQ a The novel compounds of the present invention are 2- (omega-substituted vinylene)-3,3-disubstituted-3H-indoles wherein a cyclic radical (represented by A in the formula below) which contains a secondary or tertiary nitrogen atom or an oxygen, sulfur or selenium atom, either as a substituent linked to a ring carbon atom of the radical of a cyclic compound containing an unsaturated carbon atom or as a member of the radical of a heterocyclic compound containing an unsaturated carbon atom, is linked to the terminal carbon atom of the vinylene radi- .4 cal at a carbon atom of the cyclic radical which, together with the vinylene radical, forms part of a conjugated chain of an odd number of carbon atoms linking said nitrogen, oxygen, sulfur or selenium atom to the indole nitrogen atom.

Thus, they include compounds in which the omegasubstituent is (1) an aryl radical having a hydroxyl, thiol or substituted amino group in ortho, para or other suitable position relative to the vinylene radical, or (2) a heterocyclic radical of the above type linked to the vinylene radical through a ring carbon atom.

Suitable aryl radicals carrying a hydroxyl, thiol, or substituted amino group include mononuclear and polynuclear aromatic hydrocarbon radicals and derivatives thereof which are further substituted by 1 to 4 inert substituents that are alike or different (represented by R in the formulas below); for example, halogen atoms and the following radicals; alkyl and alkoxy (especially those derived from lower hydrocarbons, and including substituted alkyl), cycloalkyl, aralkyl, aryl (especially of the phenyl, naphthyl and biphenyl series), nitro, alkylsulfonyl, arylsulfonyl, and sulfamyl radicals. Representative of such substituents are: chlorine, bromine, fluorine, methyl, ethyl, propyl, butyl, amyl, hexyl, chloroethyl, hydroxypropyl, ethoxyethyl, cyanoethyl, methoxy, ethoxy, propoxy, butoxy, amoxy, hexoxy, cyclopentyl, cyclohexyl, benzyl, phenethyl, phenyl, tolyl, naphthyl, methyl sulfonyl, ethyl sulfonyl, phenyl sulfonyl, naphthyl sulfonyl, sulfamido, N-N-dimethyl-sulfonamido and N-ethyl-sulfonamido.

Substituted amino groups include secondary and tertiary amino radicals in which one or both of the hydrogen atoms of the NH group are replaced by inert substituents (represented by R and R in the formulas bewhere R, R and R are as defined above, and R represents hydrogen, alkyl, aralkyl, cycloalkyl or aryl,

benzothiazyl radicals, .pyridyl radicals and quinolyl radi cals.

The compounds of the present invention include compounds'in which the benzo nuclei of the indole radicals are free from substituents .or are substituted by 1 to 4 inert substituents which are alike or different (represented by R above); for example, halogen atoms and the following radicals: alkyl and alkoxy (especially those derived from lower hydrocarbons), cycloalkyl, aralkyl, aryl (especially of the phenyl, naphthyl and biphenyl series), nitro, alkylsulfonyl, arylsulfonyl, and sulfamyl radicals, representatives of which are set out above.

Further, they include-compounds in which the 3,3-substituents of the 3H-indole radicals (represented by R and R in the following formulas) are alike or diiferent and are selected from the group consisting of the halogens and the following radicals: alkyl (especially those derived from lower hydrocarbons), cycloalkyl, aralkyl and aryl (especially of the phenyl, naphthyl and biphenyl series), representatives of which are set out above.

Preferred compounds of the present invention are free from chromophoric groups and from groups containing a hydrogen cation, since such preferred compounds are slightly colored or substantially colorless and therefore of special utility in compositions and systems of the types referred to above.

The compounds of the present invention correspond to the formula:

R1 IO R2 R.

C-(HC -C'Hh-A W wherein R is selected from the group consisting of hydrogen, the halogens, and nitro, alkyl, alkoxy, cycloalkyl, aralkyl, aryl, alkylsulfonyl, arylsulfonyl, and sulfamyl radicals, and when more than one may be the same or different as set out above,

R and R are each selected from the group consisting of the halogens and alkyl, cycloalkyl, aralkyl and aryl radicals, and may be the same or different as set out 2 above,

x is a whole number from 1 to 4, and especially 1 or 2, n is a whole number from 1 to 5, and especially 1 or 2, A is a cyclic radical containing an atom selected from the group consisting of secondary nitrogen atoms, tertiary nitrogen atoms, oxygen, sulfur and selenium, either as a substituent of an aryl radical or as part of a heterocyclic radical, and which radical is connected to the end of the (CH CH) radical in such manner that said atom is linked to the indole nitrogen atom by a conjugated chain of an odd number of carbon atoms. (Throughout this specification and the claims, the ranges include the limits.)

The compounds of particular value for the uses referred to above are those wherein R is hydrogen, R and R are alkyl radicals, especially lower hydrocarbon alkyl, and R and R and R are alkyl radicals.

Examples of the compounds of the invention are:

2- (4'-N,N-dimethylarnino styryl-3 ,3-dimethyl-3 H-indole 2- (4-hydroxy) styryl-3 ,3 -dimethyl-3H-indole 2- [4'- (N-2"-cyanoethyl,N-methyl) aminostyryl] -3,3

dimethyl-3 H-indole 2- (4'-N,N-diethylamino) styryl-3,3-dirnethyl-3H-indole 2- (4'-acetamido) styryl-3 ,3 -dirnethyl-3 H-indole 2- 2-hydroxypheny1butadienyl) -3 ,3 -dimethyl-3H-indole 2- 2'-( l"-methyl) indolyl 3 -ethylene] 3,3-dimethyl-3H- indole 2- 2-( 1"-methyl-2"-phenyl indolyl ('3 )-ethylene] -3,3-

dimethyl-3 H-indole 2-[ (4'-N,N-dimethylaminophenyl) 1,3-butadienyl-4] -3 ,3-

dimethyl-3H-indole The compounds of the present invention can be pre pared in various ways. The simplest method from the standpoint of availability of starting materials and apparatus required involves the condensation of a Z-methyl-f 60 3,3-disubstituted-3H-indole with a suitable aminoarylaldehyde, hydroxyarylaldehyde, or heterocyclic aldehyde, in the presence of an acid condensation agent. Preferably the condensation is carried out in the presence of a solvent (such as isopropanol), and at a temperature between," 65

about 50 C. and 180 C.

The condensation of the indole and aldehyde components by the process of our invention is carried out in the presence of an acid catalyst or condensing agent, e.g.,

phosphoric acid, hydrochloric acid, sulfuric acid, succinicr 70 acid, acetic acid, and generally substances having a pK value of at least about lO These are preferably present in at least equimolar amounts compared with the amount of 3H-indole compound present. Lesser amounts tend to decrease the reaction rate, while more, than about 10 times the molecular equivalent quantity has no greater effect on the reaction velocity than the preferred quantity. As a matter of preference, a solvent is used. Substances which are non-reactive with the reactants, but in which one and preferably both reactants are soluble can be used as solvents. In most instances, hydroxylic substances, are suitable, such as aliphatic alcohols (e.g., methanol, ethanol, propanols, butanols, pentanols, hexanols, heptanols and octanols) and glycols (e.g., ethylene glycol, diethylene glycol and trimethylene glycol). Ethers, such as diethylether, also can be used either alone or in admixture with one or more of the hydroxylic solvents. Moreover, the acid catalysts condensing agents themselves can function dually as catalysts and as solvents.

The temperature at which our novel process is carried out can be varied over a broad range. The reaction temperature is not a critical feature of the process but serves, within limits, to expedite the condensation and thus to obtain a convenient reaction period. Accordingly, tem- O peratures from about 50 C. to about 180 C. are generally preferred. Reactions carried out below about C. require inordinately long periods for completion, Whereas at temperatures much above 180 C. decomposition and side reactions may become prominent and 5 thus detract from the yield of the desired product.

A preferred method of preparing the above novel compounds in accordance with our invention comprises heating a mixture of substantially equimolecular proportions of a 2-methyl-3,3-disubsti'tuted-3H-indole and an orthoor para-(substituted-amino)aryl-aldehyde in solution in a solvent (e.g. isopropanol) under refluxing conditions, slowly adding a solution of about 2 molecular proportions of phosphoric acid in the solvent to the boiling solution and boiling and refluxing the mass for an extended period of time to insure complete condensation. The resulting product is separated from the mother liquor (e.g. by decantation), the product is dissolved in water, and the solution is rendered alkaline to Brilliant Yellow. The product which precipitates is purified by dissolving it in 0 acetone reprecipitating by dilution with dilute aqueous caustic alkali. The resulting product is separated by filtration, washed with water, and dried.

The following 3H-indoles exemplify compounds suitable for use in this process:

2,3 ,3-trimethyl-3H-indole 2-methyl-3,3 -dibenzyl-3 H-indole 3-ethyl-2,3-di-methyl-3H-indole 6-chloro-2,3 ,3 -trimethyl-3H-ind0le 4-ethoxy-2,3 ,3-trirnethyl-3 H-indole 5-sulfamyl-2,3 ,3-trirnethyl-3 H-indole 3 ,3 -di'butyl-2-methyl-5-hexylsulfonyl-3H-indole 3-benzyl-2,3-dimethyl-3-H-indole The following aldehydes exemplify substituted aryl aldehydes and heterocyclic aldehydes suitable for use in this process:

4-acetamidobenzaldehyde 4-N,N-diethylaminobenzaldehyde 4- N-fi-cyanoethyLN-methyl) aminobenzaldehyde 4- N-cyclohexyl,N-propyl) aminobenzaldehyde Z-N-N-dimethylamino-4-benzylbenzaldehyde Z-N-N-diethylarnin-obenzaldehyde 4- N-a-chloroethyl-N-methyl) aminobenzaldehyde 4- (N-phenyl aminobenzaldehyde p-hydroxybenzaldehyde o-hydroxybenzaldehyde (salicylaldehyde) 3-chloro-4-hydroxybenzaldehyde 2-bromo-4-hydroxybenzaldehyde 4-fluoro-2-hydroxybenzaldehyde 4-hydroxy-3-methoxybenzaldehyde (vanillin) 4-hydroxy-3-nitr-obenzaldehyde 4-hydroxy-3-propoxybenzaldehyde 2-hydroxy-3,S-dimethylbenzaldehyde 4-hydroxy-2,3,6-trimethylbenzaldehyde 2,4-dihydroxybenzaldehyde 1,2,5 -trimethylpyrrole-3 -carboxaldehyde Z-methyll-phenylpyrrole-3 -carboxaldehyde 1,2-dimethylindole-3 carboxaldehyde Z-methoxy indole-3-carboxalde-hyde l-methyl indole-3-carboxaldehyde 1 -methyl-2-phenylindole-3 -carb oxaldehyde 1-ethyl-2-u-naphthylindole-Il=carboxaldehyde 4-dimethylaminocinnamaldehyde 5 (p-dimethylaminophenyl pentadienal 7 (p-dimethylaminophenyl heptatrienal 9 (p-diethylaminophenyl) nonatetraenal The invention will be illustrated by the following specific examples in which the temperatures are in degrees centigrade and the parts and percentages are by weight, unless designated as parts by volume. In the latter instance, the amount signifies the volume occupied by the same number of parts by weight of Water at 4 C. It will be understood, however, that the invention is not limited to the details set out therein and that changes can be made Without departing from the scope of the invention.

Example 1 To a refluxing solution (temperature about 83) of 94 parts of 4-(N-2-cyanoetl1yl, N-methyl)aminobenzaldehyde and 80 parts of 2,3,3-trimethyl-3H-indole in 1000 parts by volume of isopropanol, a solution of 70 parts by volume of 85% ortho-phosphoric acid in 150 parts by volume of isopropanol was added dropwise during one hour. The original light yellow solution rapidly turned deep red and a tarry solid appeared in the mixture. The mass was maintained refluxing for about four hours and then cooled to ambient temperature. The supernatant liquor was descanted from the tarry product which was washed twice with 100-part (by volume) portions of isopropanol. The washed product was dissolved in 1000 parts of warm water and the solution, after being cooled to ambient temperature, was rendered alkaline to Brilliant Yellow by the addition of 65 parts by volume of 50 B. aqueous sodium hydroxide. The supernatant aqueous liquor was decanted from the precipitated tarry mass, and the latter was washed by decantation with water. The tar was dissolved in acetone (about 600 to 650 parts) and the resulting solution was added dropwise to 5,000 parts of cool water (about 20) containing 40 parts by volume of 50 Bl. aqueous sodium hydroxide. The resulting slurry of yellow solid was agitated for 1 to 2 hours and then filtered. The filter cake was reslurried in 2,000 parts of water containing 20 parts by volume of 50 B. aqueous sodium hydroxide and the slurry was agitated for several hours and then filtered. The filter cake was washed with Water and then dried in vacuo at 30.

The product thus obtained as light yellow crystals (137 parts nitrogen analysis: calculated 12.6%; found 12.04%) having a melting point of 105106.5, uncorrected, was 2 [4' (N-2"-cyanoethyl,N-methyl)aminostyryl]3,3-dimethyl-3H-indole, corresponding to the formula:

It was soluble in methanol and similar lower alcohols. When a 1% alcoholic solution was applied to filter paper impregnated with succinic acid, a bright, deep red colora- 11011 was produced instantaneously.

Example 2 In a manner analogous to that described in Example 1, 8.9 parts of 4-N,N-diethylaminobenzaldehyde were condensed with 8.0 parts of 2,3,3-trimethyl-3H-indole to give When a drop of a 1% alcoholic solution of this product was applied to filter paper impregnated with succinic acid, it gave a bright, deep bluish-red coloration instantaneously.

Example 3 A mixture of 6.1 parts of p-hydroxybenzaldehyde and 8.0 parts of 2,3,3-trimethyl-3H-indole was dissolved in 100 parts by volume of isopropanol and the solution was heated to boiling under reflux. During the following 20 minutes, a solution of 7 parts by volume of orthophosphoric acid in 15 parts 'by volume of isopropanol was added dropwise to the refluxing solution. An orange-red solid appeared in the mixture on addition of the acid solution. The mixture was refluxed for about four hours and then cooled to ambient temperature. The product was filtered off and the filter cake was washed with about 50 parts of the alcohol. The washed product was reslurried for about 16 hours in 400 parts of water containing 5 parts by volume of aqua ammonia. The slurry was filtered and the filter cake was dried.

The product thus obtained as light yellow crystals (11 partsnitrogen analysiszcalculated 5.33%; found 5.29%) having a melting point of 214-216, uncorrected, was 2-(4-hydroxy)styryl-3,3-dimethyl-3H-indole, corresponding to the 'formula:

twang... \N// It was soluble in methanol and similar lower alcohols. When a 1% alcoholic solution was dropped on filter paper impregnated with succinic acid, a bright, deep yellow coloration was produced instantaneously.

Example 4 A mixture of 8.2 parts of p-acetamidobenzaldehyde and 8.0 parts of 2,3,3-trimethyl-3H-indole was dissolved in parts by volume of boiling isopropanol under reflux. To the refluxing solution, a solution of 7 parts by volume of 85% ortho-phosphoric acid in 15 parts by volume of isopropanol was added dropwise over a twenty minute period and the resulting mixture was maintained refluxing for about 16 hours. The mass was cooled to ambient temperature and the supernatant alcoholic liquor was decanted from the tarry product. The latter was dissolved in 500 parts of hot water and, after cooling the solution to about 25, it was rendered alkaline to Brilliant Yellow with aqueous sodium hydroxide. The resulting light yellow-brown precipitate was filtered oif, washed well with water, and dried at 50 in vacuo.

The product thus obtained as light yellow-brown crystals which decomposed at 147.5 (nitrogen analysiszcalculated 8.70%; found 8.77%) was 2-(4'-acetamido)- styryl-3,3-dimethyl-3H-indole, corresponding to the formula:

75 instantaneously.

, 9 Example A mixture of 7.9 parts of 2,3,3-trimethyl-3H-indole and 11.7 parts of 1-methyl-2-phenylindole-3-carboxaldehyde in 100 parts by volume of isopropanol was heated to boiling and maintained refluxing. To the boiling mixture, a solution of 7 parts (by volume) of 85% ortho-phosphoric acid in 15 parts (by volume) of isopropanol was added dropwise over about 15 minutes. The resulting mixture was refluxed for four hours and then permitted to stand at ambient temperature for about 16 hours. The tarry condensation product, thus obtained was dis-solved in about 200 parts of acetone and the solution was poured into 1000 parts of water containing about parts of 50 B. caustic soda. The volatile portion of the aqueous mixture was evaporated off by heating the mixture on a steam bath, and the remaining red tarry oil set to a semi-solid after standing about 16 hours. It was dissolved in about 175 parts of acetone, and the acetone solution was poured into about 1000 parts of water to which about 5 parts of 50 B. sodium hydroxide had been added. The aqueous mixture was heated on a steam bath to drive off acetone, and the aqueous residue permitted to stand for about 16 hours. The resulting solid precipitate was filtered from the aqueous mixture and dried at 50 C. in vacuo.

The product thus obtained as a light yellow solid (nitrogen analysiszcalculated 7.5%; found 7.2%) which melted at 6471, uncorrected, was 2-[2'-(1"-methyl-2"-phenyl)indolyl(3")-ethylene]-3,3-dimethyl-3H indole, corresponding to the formula:

It was soluble in loweralcohols to give light yellow solutions. When a drop of a 1% solution in denatured ethyl alcohol (Formula 2B) was applied to filter paper impregnated with succinic acid, a deep orange coloration was produced almost instantaneously.

Example 6 To a hot (80) mixture of 7.9 parts of 2,3,3-trimethyl- 3H-indole and 11.7 parts of 1-methyl-2-phenyl-indole-3- carboxaldehyde in 100 parts (by volume) of glacial acetic acid, a solution of 7 parts (by volume) of orthophosphoric acid in parts (by volume) of glacial acetic acid was added dropwise. The mixture was heated to and held for 4 hours at 114 under reflux conditions. The mass was permitted to cool to room temperature and then drowned in 750 parts of water. The drowned mass was rendered alkaline to phenolphthalein by the addition of aqueous sodium hydroxide, and the aqueous layer was decanted from the red tar which precipitated. The tar was dissolved in about 400 parts of acetone, and the solution after being sludged filtered was poured into 2500 parts of water to which about 10 parts of 50 B. sodium hydroxide had been added. The brown-yellow solid which appeared was separated by filtration and dissolved in about 120 parts of acetone. This solution was poured into 1000 parts of water to which 5 parts of 50 B. sodium hydroxide had been added, and the mixture was permitted to stand for about 16 hours. The mass was heated on a steam bath to drive oif the acetone and the residue was again allowed to stand for about 16 hours. The resulting solid was separated by filtration and dried at 5 0 in 'vacuo.

The product was a light yellow solid melting at 7078 (nitrogen analysiszcalculated 7.5%; found 7.3% It had an infrared absorption pattern which was identical with the product of Example 5, and gave similar deep orange 10 colorations when dissolved in alcohol and applied to acidified filter paper;

It can thus be seen that a novel class of chromogenic compounds has been devised. These compounds, on compounds, on coming into contact with an acidic electron acceptor, turn deep shades of yellow to red. Accordingly the range of colorations obtainable with the family of chromogenic electron donor compounds has been extended to cover the entire visible range from blue to red.

In addition, the compounds of the present invention make possible the production of black colorations, by mixing in suitable proportions, the above red and yellow chromogenic electron donor compounds with compatible known chromogenic electron donor compounds which give blue to green colorations upon contact with acidic electron acceptors, as illustrated in the following example.

Example 7 The following compounds are mixed in the following proportions by weight.

55 parts of the red-producing compound of Example 1 above 15 parts of the yellow-producing compound of Example 3 above 30 parts of 4-[bis(p-dimethylaminophenyl)methyl]-morpholine of US. Patent 2,981,733.

When a 1% solution of the mixture in an alcohol (e.g. 2B denatured ethyl alcohol) is contacted with paper treated with clay or succinic acid, an intense black coloration develops in about a minute.

It will be realized by those skilled in the art that the invention is not limited to the details of the foregoing description and that changes can be made without departing from the scope of the invention.

Thus, instead of the 2,3,3-trimethyl-3H-indole and aldehydes employed in the above examples, other suitable 2-methyl-3,3-disubstituted 3H-indoles and aldehydes can be used; for example those set out above. Further, instead of the aldehydes, the corresponding acetals or related aldehyde-precursors, or the corresponding methylene dichlorides or methylene dibromides may be employed (such as, 4-acetamidobenzal chloride, 4-dimethylaminobenzal bromide, etc.).

Further, instead of preparing the compounds by the above procedure, they may be prepared by the reverse condensation; namely, by condensing the related 2-(3,3- disubstituted-3H-indolylidene) acetaldehyde with a suitable cyclic component adapted to provide a Z-omega substituted vinylene compound of the above type preferably under the influence of an acid catalyst or condensing agent and in a suitable solvent medium.

For example, 2-(3,3-dimethyl-3H-indolylidene) acetaldehyde can be condensed with 3-H-indole to produce 2- [2-(indolyl (3 -ethylene] -3,3 -dimethyl-3 H-indole. Similarly, it can be condensed with other suitable compounds containing active hydrogens.

We claim:

1. Z-(omega-substituted vinylene) 3,3-disubstituted 3H- indole corresponding to the formula:

I'll C-Ra R is selected from the group consisting of hydrogen,

chlorine, lower alkyl, lower alkoxy, lower alkyl sulfonyl, phenylsulfonyl and sulfamyl,

R and R are each selected from the group consisting of lower alkyl and benzyl,

n is a whole number from 1 to 5, and

1 1 1 Y is selected from the group consisting of hydroxy,

lower alkanoylamino, and N-(lower alkyl), N-(cyano-lower a1kyl)amin0 and is in the 2- or 4-position.

2. 2-( omega N (lower alkanoyl)aminophenyl-vinylcne)-3,3-di-(lower a1kyl)-3H-ir1dole, as claimed in claim 1.

3. 2-acetamidostyryl-3,3-dimethyl-3H-indole.

4. 2 (omega hydroxyphenyl vinylene)-3,3-di-(l0wer alkyl)-3H-indole, as claimed in claim 1.

5. 2-hydroXystyryl-3,3-dimethyl-3H-indole.

6. 2-(omega-substituted vinylene) 3,3-disubstituted-3H- indole as claimed in claim 1, wherein R is hydrogen,

R and R are each lower alkyl,

n is 1 or 2, and

Y is hydroXy or N-(methyl), N-(p-cyanoethyDamino.

7. 2-(ornega-substituted vinylene) 3,3-disubstituted-3H- indole as claimed in claim 6, wherein R and R are each methyl.

8. 2-[4-(N 8 cyanoethyl, N methyl)aminostyryl]- 3,3-dimethyl-3H-indole.

1 2 References Cited UNITED STATES PATENTS 2,140,248 12/1938 Retter et a1. 260240.9 X 2,164,793 7/ 1939 Winter et a1. 260240.9 2,179,895 11/ 1939 Muller et al. 260240.9 2,320,654 6/ 1943 Riester 260240 2,953,561 9/1960 Doorenbos 260240 3,095,303 6/1963 Sprague et a1. 260249.9 X 3,100,703 8/1963 Sprague et al. 260240.9 X 3,102,810 9/1963 Sprague et a1. 260240.9 X 3,113,825 12/1963 Streck 260240.9 X

OTHER REFERENCES Brooker et al.: J. Am. Chem. Soc., vol. 73, pages 5336- 15 6337, 5341, 5345, 5348 and 5350 to 5356, (1951).

JOHN D. RANDOLPH, Primary Examiner. 

1. 2-(OMEGA-SUBSTITUTED VINYLENE) 3,3-DISUBSTITUTED 3HINDOLE CORRESPONDING TO THE FORMULA: 